There are such devices currently widespread that can handle various types of digital data such as music contents, moving image contents and still image contents (hereinafter, referred to as contents data) irrespective of whether they are paid or charge-free contents. These devices are used in the following ways: a user voluntarily rips the contents data from a music CD which he/she purchased so as to put it in a PC, records the ripped contents data in the PC on a semiconductor recording medium, and enjoys the contents data played on a compact semiconductor player; or a user, after paying a predetermined rate, downloads into a PC or any other terminal like a mobile phone contents data, such as music, moving images and books provided from a contents provider by way of the Internet or a mobile telephone network, then records the downloaded contents on a semiconductor recording medium and enjoys the contents data played on a compact semiconductor player.
These contents data are in most cases protected by a copyright protection system when the data is distributed through a distribution channel or managed by devices so that any illegal duplication of the data can be prevented from happening. For example, the content data is encrypted according to a certain method, and a key used in the encryption is delivered/retained securely as rights information of the contents data as well as its usage-restriction information of the contents data. In general, such a technology for controlling/restricting the usage and duplication of the contents data is called digital rights management (hereinafter, referred to as DRM technique). The technique includes, for example, specifications which are installed in recording media such as DVD, BD and SD memory cards, and specifications run on a personal computer by application software such as Media Player (registered trademark) and iTunes (registered trademark). In an example of a contents data management method actualized by the DRM technique, each of the encrypted contents data and the rights information corresponding thereto respectively includes ID information which can be uniquely identified and managed, and the contents data is retrieved based on the rights information corresponding to the contents data and the ID information of the contents data corresponding to the rights information.
There are a variety of other recording media on which digital data can be recorded other than the semiconductor recording medium described earlier, examples of which are magnetic discs, optical discs, and magneto-optic discs. Of these media, a semiconductor recording medium is compact and light, and has been rapidly improved in recent years in terms of capacity, speed and price reduction. Therefore, semiconductor recording media are used in various electronic devices such as digital cameras, mobile telephones, mobile music players, television receivers and DVD/BD recorders. Typical examples of the semiconductor recording media are SD memory cards, SDHC memory cards, memory stick (registered trademark) and compact flash (registered trademark). Such semiconductor recording media provided with a copyright protection function as SD memory cards and SDHC memory cards are particularly used in a number of different devices.
An example of the DRM technique used when encrypted contents data and the rights information corresponding thereto are stored in a semiconductor recording medium is given below. According to this technique, the semiconductor recording medium is provided with a protected region which can be accessed only after the recording medium and an access device, which is a reproducer or a recorder, mutually verify that they are authentic, and an normal region which can be accessed without the verification of the authenticity therebetween. Then, the rights information is stored in the protected region, while the encrypted contents data is stored in the normal region.
One of the DRM techniques is a management method wherein the stored contents data and the rights information are associated with each other for management purpose based on the ID information retained by each. In this technique, internal operations of the access device (reproducer) performed when the contents data stored in the semiconductor recording medium is utilized are supposed to be
To read contents data to be reproduced from the semiconductor recording medium; and
To read the rights information corresponding thereto from the protected region of the semiconductor recording medium based on the ID information which uniquely identifies the rights information.
The rights information is read (obtained) in different manners depending on how the rights information is stored in the protected region. For example, the rights information is stored as a file on a structure managed by a file system such as FAT in the protected region, the rights information and related information in the protected region are recognized and obtained through the use of a file system on the access-device side, and required information is retrieved out of the obtained information by the access device based on the ID information. According to the method, since it is necessary to handle the rights information which is highly confidential inside the access device, the access device needs to be provided with a confidentiality function (such a function that can prevent reverse engineering (for example, tamper resistance)). Moreover, it is necessary to retrieve the rights information at a high speed in order to speedily process (for example, reproduce) the contents data, and the retrieving speed depends on functions of the access device.
As another approach for reading (obtaining) the rights information, the semiconductor recording medium receives the ID information, and the semiconductor recording medium per se efficiently manages and retrieves the rights information stored therein. An example of the approach, which is a method relating to an IC card, is disclosed in the Patent Document 1, wherein a method of efficiently managing internal data by reducing a volume of memory consumption is disclosed.    Patent Document 1: 2005-122414 of the Japanese Patent Applications Laid-Open